Our endocrine system is a complex system that is essentially responsible for maintaining homeostasis in the body. That is, even as the world is ever changing, our body needs to stay about the same. Our body temperature needs to be maintained somewhere around 98.6 and our blood pH cannot deviate without serious consequences.

Endocrine System Hormones

One important endocrine system function is the secretion of hormones.

Hormones are chemicals secreted by an endocrine gland that bring messages to other parts of the body. Hormone means “impetus” and they alter the metabolic activities of their target cells. In so doing they are a catalyst for chemical changes in the body.

Different types of hormones regulate:

muscle growth

reproductive and sexual functions

energy

mood

digestion

Generally, endocrine system hormones are secreted in small amounts and they work in a constant, steady fashion. Hormones are carefully regulated in the body to achieve homeostasis.

Homeostasis is the ability of a system to maintain a stable and constant condition. For example, there are numerous mechanisms in our bodies to regulate our internal temperature in spite of the fluctuating external temperature. In this way, our bodies maintain a stable temperature of around 98.6 degrees.

Negative feedback loops are a way to understand how hormone levels in the blood remain stable. If a substance falls below normal levels in the body, the corresponding endocrine gland releases more of its particular hormones. When the substance has reached its normal levels, the endocrine gland is no longer stimulated to release extra amounts of the hormone.

This negative feedback loop can be easily compared to a house with electric heat regulated by a thermostat. The thermostat is programmed to keep the house at a particular temperature. If the temperature inside the house becomes too cold, the heat kicks in to warm it up. Once the desired temperature has been met, the heat turns off.

There are two main groups of endocrine system hormones:

steroids (which come from cholesterol)

non-steroids (which come from amino acids)

Endocrine system diseases usually involve hypERsecretion (too much) of hormones or hypOsecretion (too low) of hormones.

Endocrine System Glands

The organs of the endocrine system are made up of ductless glands. The glands of the endocrine system play a major role in maintaining homeostasis throughout the body. They are responsible for secreting endocrine system hormones.

HypothalamusThe hypothalamus gland is located above the brain stem in the center of the skull. This important endocrine system gland links the nervous system with the endocrine system via the pituitary gland. It is responsible for regulating a variety of functions throughout the body, including body temperature, fatigue, circadian rhythms, hunger and thirst. It controls almost all of the internal organs. You can think of it as the major control center for the autonomic nervous system.

Pineal bodyThe pineal gland is a small cone-shaped gland about the size of a pea and found in the brain. It secretes the hormone melatonin, which aids our sleep cycle.

PituitaryThe pituitary gland is connected to the hypothalamus gland by a short stalk. It consists of two lobes and each lobe has different functions. This tiny gland plays a major role in many of the functions of the human body. Hormones and neural impulses from the hypothalamus directly influence the hormones secreted by the pituitary gland.

ThyroidThe thyroid gland is a butterfly-shaped gland found in front of the trachea on the front of the neck. It has a right and left lobe. When stimulated with the thyroid stimulating hormone (TSH) from the anterior pituitary gland it releases T3 and T4. In order to operate well the thyroid gland needs to have an adequate supply of iodine and tyrosine as well as other important minerals such as selenium, manganese, magnesium and zinc to name a few.

ParathyroidsThere are usually four parathyroid glands located on the posterior side of the thyroid gland. These small glands secrete the parathyroid hormone.

ThymusThe thymus gland is a soft structure located in the mediastinum, just above the heart. This gland plays a big role in the immune system development of infants and children. As we age, the gland begins to shrink and is actually quite small in adults.

The major role of this gland is the production of a particular type of lymphocyte called T-cells. These important immune system cells can attack and destroy foreign antigens. One way to stimulate or boost thymus function is to bang on your chest, Tarzan style.

AdrenalsThere are two adrenal glands in the body. They are located on top of each of the kidneys. Each gland contains two parts that have distinctive endocrine system functions. They are named the inner adrenal medulla and the outer adrenal cortex.

Both aspects of the adrenals are responsive to stress. The following forms of stress can affect the adrenal glands: physical stress such as feeling threatened, lack of sleep, overwork, over exercise, etc; emotional stress due to any reason; thermal stress such as extreme variations in temperature; chemical stress due to endocrine dysfunction, environmental toxins, improper diet, food allergies, etc.

When the body experiences stress, the sympathetic nervous system stimulates the release of the hormones epinephrine and norepinephrine from the adrenal medulla. These hormones have a strong and lasting influence on the body’s fight or flight responses and allow the body to prepare to meet intense situations. They influence the cardiovascular system by increasing heart rate, blood pressure and thereby cardiac output. The metabolic rate is increased and blood sugar is increased by the conversion of glycogen to glucose. The respiratory passages are dilated for increased respiration. The result is a hyper vigilant body ready to take flight or fight as necessary.

Cortisol inhibits inflammation and provides resistance to stress. It promotes regular metabolism and helps to obtain glucose from non-carbohydrate sources. Too much secretion of cortisol results in a western diagnosis of Cushing’s disease while too little results in a western diagnosis of Addison’s disease.

Androgens or male sex hormones are also secreted by the adrenal glands. These have a limited effect in adult males and contribute to a woman’s libido.

Pancreas

The pancreas is an organ located just below and behind the stomach.

The pancreas is made up of two different kinds of tissues and also has two distinct functions. It is classified as both an endocrine gland and an exocrine gland.

As an exocrine gland the pancreas secretes digestive enzymes into the small intestine. These enzymes play a role in breaking down carbohydrates, proteins and fats.

As an endocrine gland the pancreas secretes hormones that help to regulate blood glucose levels. There are four cells that achieve this function: alpha cells, beta cells, delta cells and polypeptide (F) cells.

Summary of Endocrine System Facts

The endocrine system plays an important role in helping your body maintain homeostasis. The endocrine system function allows your body temperature to stay the same despite environmental changes, or it can purposefully raise your body temperature in an attempt to overcome an illness such as the flu.

The endocrine system also plays important roles for your immune system health, nervous system health and reproductive health.